Before
enrolling in graduate school in 1979, I gained extensive research experience
with electrophoretic techniques that offered advantages for bioseparation
processes in the microgravity environment of Earth orbit. I studied isolation
of gammaglobulins from extracorporeal blood circulation using forced-flow
electrophoresis (University of Edinburgh Veterinary School,1969-72);
isotachophoresis and isoelectric focusing of cells as separative processes in
zero gravity (University of Arizona Engineering Experiment Station, 1973-1976);
and electrophoretic cell separation using microspheres (Space Sciences
Laboratory, Marshall Space Flight Center, Huntsville, Alabama, 1977-1979). I
was afforded unusual independence for a predoctoral researcher, but also
benefited enormously from close mentorship, primarily by Dr. Milan Bier, the
renowned electrophoresis theoretician and NASA bioseparations consultant. In
1975, I contributed blood samples and loaded the MA-011 isotachphoresis module
prior to launch on the Apollo-Soyuz orbital mission. My early papers (see
below), were the first to report bulk electrophoretic isolation of human
gammaglobulin, and the use of immunomicrospheres to separate cell populations
with overlapping electrophoretic mobility profiles.

Dr.
George Sachs, discoverer of the gastric H,K-ATPase responsible for acid
secretion, recruited me from NASA to the physiology PhD program at UAB. My
dissertation described creation and characterization of the first monoclonal
antibodies against H,K-ATPase alpha subunit and discovery of
secretagogue-induced H,K-ATPase translocation from parietal cell tubulovesicles
to the secretory canaliculus. My postdoctoral and subsequent research as an
NIH-funded P.I., first at UCLA and later at MUSC, leveraged the epitope
specificity of monoclonal and site-directed polyconal antibodies to gain
insight into H,K-ATPase expression, membrane topology, gastric and renal
localization, and function, as documented below. These antibodies have been
utilized in innumerable gastric physiology studies world-wide through licensing
agreements with EMD Millipore Corp.

Solution
at 2.8Å resolution of the first P-type ATPase structure in 2000 by X-ray
crystallography de-emphasized the value of classical membrane protein
structure-function studies based on epitope mapping. Seeking new challenges,
and intrigued by H. pylori’s ability to withstand the acidic assault
launched by gastric H,K-ATPase, I proposed and tested the novel hypothesis that
amongst its defenses the bacterium deploys targeted inhibition of cellular
H,K-ATPase gene expression. My work in this field, cited here, remains the most
comprehensive molecular account to date of how H. pylori accomplishes
this feat. H. pylori produces virulence factors that hijack host cell
signaling pathways to mobilize NF-kB
p50 homodimers to the nucleus where they bind to the HKa gene promoter, repressing
transcription. These factors also up-regulate parietal cell miR-1289, which
restricts translation of HKa mRNA.

My
discovery that H. pylori infection of gastrointestinal cells in culture
led to repression of transfected HKa promoter-reporter constructs within a few hours of
infection helped explain the onset of transient hypochlorhydria. This
characteristic of human H. pylori infections is not marked by
morphological damage to parietal cells. Since IL-1b is a potent acid inhibitor, we investigated whether H.
pylori’s acid inhibition was mediated by IL-1
b. Concurrently we investigated mechanisms whereby H. pylori is
able to breach the gastric epithelial barrier. In both cases we provided the
first evidence for IL-1 b interaction
with HKa
gene transcription and its role in activation of matrix metalloproteinases.
These findings provided mechanistic underpinnings for the role of host IL-1 b polymorphisms in pathophysiology of H.
pylori infection, and identified yet another mechanism of H. pylori-induced
increase in mucosal permeability.

Over
the years, my engagement with mechanisms and repercussions of gastric acid
secretion led to contributions in closely related fields, and these are
documented in part here. The first citation documents one of several papers
addressing expression of H,K-ATPase in relatively ancient species and/or
extra-gastric locations. The extraordinary specificity and high affinity of my H,K-ATPase
a subunit monoclonal antibody HK 12.18
was finally localized to a carboxy-terminal DMDPSEL heptapeptide in the HKa subunit. (ref. b). My interest in novel
therapeutic inhibition of gastric acid secretion is exemplified in ref. c, as
is my discovery of miR-1289 and its potential as an alternative to PPI
anti-secretory approaches (cited in my Personal Statement above). Finally, my
proteomic approach to early detection of esophageal carcinomas, the first of
its kind, was inspired by the realization that circulatory perfusion of tumors
must populate plasma with protein and/or peptide signatures diagnostic of
disease.